This invention relates generally to processes for modifying textile fibers. More specifically, the present invention relates to apparatus for converting a continuously advancing multifilamentary yarn into a staple-like yarn.
A primary complaint regarding today's synthetic yarns is that their method of manufacture presents a product, though satisfactory from a dyeing and handling use, having a touch or hand when in final form that is less than satisfactory. The filaments are formed utilizing spinning apparatus which cause the surface of the filaments to be substantially smooth. For example, when formed into a garment structure, these smooth filaments have a tendency to be cold to the touch and generally lack the feel that one has become to expect from materials made of natural fibers, like cotton and wool.
In view of this drawback of synthetic filaments, yarn producers and garment manufacturers have sought to modify filament structures in a number of ways over the years. In one method, the yarns are cut into small segments called staple fibers and passed through apparatus such as open spinning machines which reform the staple fibers into a yarn. In the staple fiber yarn (sometimes referred to as spun yarn from the spinning operation) the ends of the various cut lengths protrude from the yarn, trapping air thus producing a feel more like the natural yarns the process attempts to simulate.
It has also been known to crinkle and twist the continuous filaments in a manner that causes the filaments to retain their contorted shape to some extent, and this texturing of the continuous filaments also tends to produce a warmer, less harsh feel than non-textured filaments.
Means for passing a barbed needle through a continuous multifilament yarn to abrade the yarn or break a small fraction of the filaments in the yarn has also been used to give the yarn a staple effect. Such an apparatus is shown in U.S. Pat. No. 4,674,271. The '271 apparatus requires intermittent passage of the yarn through the device. As disclosed in that patent, the lengthwise motion of yarn is stopped while a barbed needle is passed through the yarn. When the needle is retracted, the yarn is moved forward again. One drawback in this start/stop method of simulating staple yarn is the resultant lost process efficiency.
An apparatus for continuously bulking yarn is disclosed in U.S. Pat. No. 3,208,125. Barbed needles project periodically from a wheel to displace (entangle) the filaments of a continuous filamentary yarn. It is disclosed that sometimes the needles break a filament to produce a yarn with the appearance of spun yarn. A major drawback of the apparatus is that the action of the needles on the yarn tends to lift the yarn from the path so that the needle does not pass completely through the yarn as is required for efficient entangling. It is necessary to appropriately tension the yarn in the needle path.